A consideration on stability and control performance based on generalized structure for stable model reference adaptive control system

This paper proposes a new analytical method for the stability and the control performance of a robust model reference adaptive control system (MRACS). In order to show the uniform boundness of the input and output (I/O) signals of controlled object, the past typical studies evaluate the upper bound of many signals related to the I/O signals with a certain norm, and substitute those inequalities recursively. Consequently, those results seem conservative, and raise the following problems; it is not easy to understand how the stabilization of robust MRACS is essentially achieved, and those results do not provide information enough to realize a robust MRACS which has sufficient stability margin and better control performance. On the other hand, this paper reveals an equivalent feedback system to the main loop of robust MRACS, and uses the notion of finite-gain L_2δ stability in the analysis. These are the keys to avoid the conservativeness caused by the manner of the inequality evaluations. As a result, it seems that the results of this paper might solve the above-mentioned problems.